The present invention relates to an improved fixed shank plow anchor. While fixed shank plow anchors are known per se, Applicant is unaware of any such anchor including all of the features and aspects of the present invention. The following prior art is known to Applicant:
U.S. Pat. No. 1,974,933 to Taylor discloses a plow-type anchor having a shank and a plow pivotably connected together. Taylor discloses that the center of gravity of the anchor is well forward of a line between the hinge and the rear end of either blade. However, Taylor does not specify particularly where the center of gravity is to be located. In fact, it would be impossible for the center of gravity of the Taylor anchor to be rearward of the specified line. In contrast, the present invention contemplates specifically locating the center of gravity of the anchor within the shank and particularly specifies use of a fixed shank with no pivotable relation between the shank and plow. Furthermore, the present invention contemplates the use of a nose weight having a spike or fin mounted at the front edge of the plow.
U.S. Pat. No. 2,507,563 to Farren discloses a folding plow anchor having a hinged connection between the shank and the plow. The present invention differs from the teachings of Farren as contemplating a fixed connection between the shank and the plow and other features as will be described in greater detail hereinafter.
U.S. Pat. No. 4,397,256 to Bruce discloses an anchor having symmetric flukes and, in one embodiment, a fixed connection between the shank and the flukes. Bruce fails to disclose the particular contemplated center of gravity of his anchor nor does he disclose other features of the present invention including the use of a spike or fin at the forward end of a plow.
U.S. Pat. No. 4,602,588 to MacLean discloses an anchor having a shank generally perpendicular to the flukes and including a central opening between the flukes. The present invention differs from the teachings of MacLean as contemplating a shank fixedly connected to a fluke at a shallow acute angle.
U.S. Pat. No. 4,676,184 to Ogg discloses a flexible shank anchor. In the sole embodiment disclosed in a plow-type fluke, Ogg discloses a pivotable connection between the shank and the fluke.
U.S. Pat. No. 5,138,967 to McCarron et al. discloses a marine anchor having a shank fixedly connected to the fluke and a center of gravity between the fluke and the shank and forward of the connection therebetween. In contrast, in the present invention, the center of gravity of the inventive anchor is located within the shank.
U.S. Pat. No. 5,188,055 to Kershner discloses an adjustable boat anchor having a shank fixedly connected to a fluke and with a slot in the shank allowing sliding of the connection to the shank along the length thereof. Kershner discloses a chamber designed to be filled with a weighted material to allow adjustment of the weight and center of gravity of the anchor. In contrast, in the present invention, the center of gravity is specified as being located within the shank in the connection between the shank and the fluke and the present invention includes the further provision of a spike located centrally of the fluke and at the forward end thereof.
British Patent Specification 2 035 242 to Smith discloses an anchor not of the ploughshare type and having a center of gravity located between the shank and the fluke forwardly of the connection therebetween. In contrast, the present invention contemplates a plow-type anchor having a fixed connection between the shank and the fluke and a center of gravity located within the shank in the connection between the shank and the fluke.